Portable Power Station for a Fridge: Sizing Guide

When the power goes out, or when you're off-grid or on the move, keeping your fridge running becomes a key concern. A good portable power station for fridge use can make all the difference. But fridge loads come with regular running power, and a heavy surge when the compressor kicks in.So you’ll need to size both the inverter output and the battery capacity correctly.

Understanding fridge power requirements: Watts, surge & cycles

Running watts (steady state)

Your fridge draws a certain number of watts while the compressor is running and the system is actively cooling. According to one manufacturer's guide: mini fridges ~50-100W, standard home fridges ~100-800W depending on size and age.
For example, many modern efficient models draw around 150-300W while active. 

Surge (starting) power

When the compressor starts up, it draws a burst of power far higher than the steady running load. Many fridges require 2-6× their running current during start-up.
For example, a fridge that runs at 150W might surge to 300-450W or more just to kick on.
If your portable power station cannot handle that surge, the fridge may fail to start or may trip the inverter.

Duty-cycle and real-world run time

Fridges don’t run continuously at full load; the compressor cycles on and off. You might estimate that a fridge is actively cooling 30-50% of the time, depending on ambient temp, how often you open the door, insulation, how full it is.
Therefore, runtime estimates based purely on steady watts will be conservative. But you should still size for the worst case.

How to calculate what size portable power station you need

Step 1: Determine your fridge’s specs

Check the label (inside fridge, near compressor, or back). Look for running watts (or amps × volts) and ideally starting amperage or “locked rotor amp” (LRA) if given. If only amps given: Watts ≈ Amps × Volts (e.g., at 120V).
If unknown, a rough estimate: 200W running, 400-600W starting for mid-size fridge is common. 

Step 2: Decide how long you want it to run

Do you need backup for a few hours, overnight, or a full day? For example, if your fridge draws 200 W and you want 8 hours: 200 × 8 = 1,600 Wh required (before losses).
Because of cycling, you might need less—but plan conservatively.

Step 3: Choose battery capacity (Wh)

Battery capacity in watt-hours (Wh) tells you how much energy is stored. Many guides say: “A 500Wh station can run a 100W fridge for ~4-5 hours.”
So for a 200W fridge, you’d need roughly 1,000Wh to hit ~5 hours (200×5 =1,000Wh) plus inefficiencies.
Consider inverter efficiency (~90-95%), so maybe factor an extra 10-15% overhead.

Step 4: Ensure inverter output & surge rating are sufficient

Ensure the station’s continuous AC output (Watts) is above your fridge’s running wattage, and the surge rating is above the fridge’s start-up wattage.
For instance: if fridge runs 200W but surges to 600W, pick a station with continuous ≥200W (ideally much higher for headroom) and surge capacity ≥600W.
One blog warns: “If your fridge uses 150 W and needs 400 W to start, then your power station must handle at least 150 W running and 400 W surge.” 

Step 5: Add margin & optionally charging options

• Add 20-30% extra Wh capacity to deal with door openings, ambient heat, inefficiencies.
• If you’ll recharge via solar or AC quickly, you might choose a smaller battery because you’ll top it up.
• Ensure the station supports pass-through or charging while discharging if you’ll keep it topping while fridge runs.

Example sizing scenarios

Scenario A: Compact fridge, short backup

• Fridge running 120W, surge ~350W
• You want ~4 hours runtime.

• Energy needed = 120×4 = 480Wh → add 20% → ~576Wh.
• Station capacity ~600Wh is minimal but okay for short term.

• Ensure inverter continuous output ≥200-300W, surge ≥350-400W.
• Good for short power outage or camping.

Scenario B: Standard home fridge, overnight backup

• Fridge running ~250W, surge ~600W
• Want ~8 hours runtime.

• Energy needed = 250×8 = 2,000Wh → add 20% → ~2,400Wh.

• Inverter continuous output ≥300-400W, surge ≥600-1000W.
• This gives you're good for overnight plus next morning.

Scenario C: Full-size fridge + freezer + devices for 24h

• Combined load ~400W (fridge+freezer+lights), surge maybe 1,000W.
• 24-hour runtime: 400×24 = 9,600Wh → add 30% → ~12,500Wh.
• You’d need a large portable power station (>10kWh) or solar + recharge.
• Many standard power stations won’t handle this without recharge or large size.

Spec features you’ll want for fridge use

Here are what to prioritize when picking a station for your fridge:

• Pure sine wave inverter: Compressor motors prefer clean sine wave. Cheap or modified sine may harm.
• High surge rating: Ensure the peak watt rating covers start-up.
• Battery chemistry: LiFePO₄ (LFP) is best for many cycles and deep discharge.
• Multiple output ports: AC outlets (for fridge), USB/12V for other devices.
• Pass-through / simultaneous use & recharge: Useful if you can support solar/AC charging while running.
• Cooling/ventilation: Fridge load runs for long durations; ensure the station can handle thermal loads.
• Display/monitoring: Real-time wattage and remaining time help you manage usage.
• Recharge flexibility: Solar input, AC wall, vehicle DC make a big difference when standby time is long.
• Portability & weight: Larger battery = heavier. Consider how you plan to move it.

Tips for maximizing runtime and fridge safety

• Pre-cool the fridge before the outage or before switching onto the station so load is lower initially.
• Minimize door openings—every open door adds load.
• Keep ambient temperature moderate—hot rooms make the compressor work harder.
• Run other devices separately or delay them—fridge gets priority.
• Use a watt-meter to measure actual fridge running watts and surge—you’ll size more accurately.
• Recharge when possible—if you have solar or wall input, topping up keeps the station ready for the next cycle.
• Keep some headroom: don’t size exactly to the fridge’s specs; you want margin for safety and lesser battery stress.
• Check warranty/specs: Some fridges require UPS or uninterrupted power; small pauses or dips may affect temperature.

Frequently Asked Questions

Can a portable power station run a refrigerator?

Yes—but only if the station is sized properly for both the fridge’s running watts and its starting surge, and the battery has enough capacity (Wh) for the desired runtime. Guides consistently show: if you pick a station with sufficient surge output and Wh capacity, you can run a fridge for hours. 

How many watts does a fridge typically use?

It varies a lot: mini-fridges ~50-100W, standard home fridges ~150-400W running, and surges can hit 2-3× or more of running watts. One source says: 100-800W running typical for household fridge. 

What battery capacity do I need to run my fridge for, say, 8 hours?

Use the formula: Runtime ≈ (Battery Wh × efficiency) ÷ Running Watts.
Example: fridge 250W, 8 hours → 250×8 = 2,000Wh required. With efficiency ~0.9 → ~2,222Wh. Add margin → ~2,400Wh station capacity recommended.

What happens if surge rating is too low?

If the inverter cannot meet the surge when the compressor starts, the fridge might fail to start, the station may shut off or trip protection, or the compressor may cycle improperly causing wear. Many user-forums caution this exact issue. 

Can solar recharge the station while running a fridge?

Yes—if your station supports pass-through use and has solar input. This is especially useful for off-grid or longer durations. Many guides recommend solar input to extend runtime.

Final thoughts

When you want a portable power station for fridge use, you’re wise to focus on two key axes: inverter output (and surge capacity) and battery capacity (Wh for runtime). For short durations or compact fridges, a smaller station may suffice. For standard home fridges, overnight backups, or fridge + additional loads, aim higher.

Match the load (watts), add margin for surge and inefficiencies, and size the battery accordingly. Use the sizing steps above to decide what model fits your lifestyle. With the right station, you’ll keep your food safe, enjoy peace of mind during blackouts or off-grid use, and get reliable portable power.